Tips for Troubleshooting Your
When troubleshooting, pay careful attention to these general warnings
ATTENTION: Have all personnel remain clear of the controller
and equipment when power is applied The problem may be
intermittent and sudden unexpected machine motor could result
m injury Have someone ready to operate an emergency-stop
switch in case it becomes necessary to shut off power to the
controller equipment. Also, see NFPA 70E Part II for additional
guidelines for safety related work practices.
Never reach into a machine to actuate a switch since unexpected
machine motion can occur and cause injury.
Remove all electrical power at the main power disconnect
switches before checking electrical connections or inputs/outputs
causing machine motion.
If installation and start-up procedures detailed in chapters 5, 6, and 7 were followed
closely, your SLC controller will give you reliable service If a problem should occur, the
first step in the troubleshooting procedure is to identify the problem and its source.
The SLC 500 controller has been designed to simplify troubleshooting procedures By
observing the diagnostic indicators on the front of the power supply, processor unit and
I/O modules, the majority of faults can be located and corrected These indicators, along
with error codes Identified in the programming device user manual and programmers
monitor, help trace the source of the fault to the users input/output devices, wiring, or the
Before working on a SLC 500 modular system, always remove the power supply input
power at the main power disconnect switch.
The power LED on the power supply indicates that DC power Is being supplied to the
chassis. The LED could be off when incoming power is present.